Gate controlled photocurrent generation mechanisms in high-gain In2Se3 phototransistors

TL;DR

This paper demonstrates gate-tunable photocurrent mechanisms in In2Se3 phototransistors, enabling high gain and fast response by controlling photogating and photoconduction processes, achieving record sensitivity among 2D materials.

Contribution

It introduces a method to modulate photocurrent generation mechanisms in In2Se3 phototransistors via gate voltage, enhancing speed and sensitivity of 2D material photodetectors.

Findings

Achieved ultra-high gain of approximately 9.8 x 10^4 A/W.

Demonstrated gate-controlled switching between photogating and photoconduction.

Inferred detectivity of about 3.3 x 10^13 Jones, among the highest for 2D materials.

Abstract

Photocurrent in photodetectors incorporating van der Waals materials is typically produced by a combination of photocurrent generation mechanisms that occur simultaneously during operation. Because of this, response times in these devices often yield to slower, high gain processes which cannot be turned off. Here we report on photodetectors incorporating the layered material In2Se3, which allow complete modulation of a high gain, photogating mechanism in the ON state in favor of fast photoconduction in the OFF state. While photoconduction is largely gate independent, photocurrent from the photogating effect is strongly modulated through application of a back gate voltage. By varying the back gate, we demonstrate control over the dominant mechanism responsible for photocurrent generation. Furthermore, due to the strong photogating effect, these direct-band gap, multi-layer phototransistors produce ultra-high gains of (9.8 +- 2.5) x 10^4 A/W and inferred detectivities of (3.3 +- 0.8) x 10^13 Jones, putting In2Se3 amongst the most sensitive 2D materials for photodetection studied to date.